During the Northern Song Dynasty, Kaifeng became a worldwide metropolis. The important reason was that the Grand Canal, which was excavated during the Sui Dynasty, became the main transportation artery for the political and military center of the north and the economic center of the south.

The Grand Canal was the economic and logistical backbone of the Song Dynasty, to the point that the era is often called "the canal-centered era." It functioned as the main artery connecting the fertile, agricultural "economic center" of the south with the political and military center of the north, specifically the capital, Kaifeng. By allowing for the mass transport of grain, salt, and luxury goods like silk, the canal facilitated a "commercial revolution" and the world's first true "urbanization" in Kaifeng. It supported the Song's massive standing army by ensuring a steady supply of northern border troops and helped stabilize the economy through efficient tax collection in kind (grain). Without the Grand Canal, the Song Dynasty would have struggled to maintain its centralized power and sophisticated market economy. Its presence directly led to the development of early banking, paper money, and a vibrant merchant class that defined the cultural "Golden Age" of the Northern Song.